Multi-Component Bladed Rotor for a Turbomachine

ABSTRACT

A multipart bladed rotor ( 1 ) for a flow machine, particularly a gas turbine or steam turbine or an axial compressor, has at least two disks ( 2 ) whose front sides, which face one another, are connected to one another, particularly by positive engagement, in a separating plane ( 7 ) so as to be fixed with respect to rotation relative to one another, wherein a groove ( 10 ) for receiving a blade root ( 14 ) of at least one rotor blade is formed in the separating plane.

The invention is directed to a multipart bladed rotor for a flow machine, particularly a gas turbine or steam turbine or an axial compressor, according to the preamble of claim 1, and to a flow machine having a rotor of this kind.

Bladed rotors such as those used, for example, as compressor rotors in the compressor area of a gas turbine rotor are often formed of multiple parts comprising individual disks which are connected to one another. Every stage of the compressor can be provided with its own disk or a plurality of rows of blades, each forming a stage, can be arranged on a disk which is known as a multidisk.

Multipart bladed rotors of this kind according to the preamble of claim 1 are known, for example, from EP 1 728 973 A1 or DE-OS 26 43 886, in which the individual disks are clamped together axially by tie rods and secured to one another so as to be centered relative to one another and fixed with respect to rotation relative to one another by Hirth serrations which are formed axially between the blade rows.

For mechanical reasons and in order to prevent interruptions in flow, a spur toothing of the kind mentioned above is usually arranged on a diameter which is smaller than the outer diameter of the rotor. In order to produce a radially inner spur toothing of this kind, a free space must be provided to allow sufficient room for the tool to be withdrawn. This disadvantageously increases cost on material, manufacturing and assembly because this free space must be closed with a corresponding filling piece when the rotor is assembled in order to prevent interference of the flow.

FIG. 2 is a partial cross-sectional view through the separating plane 7 a of a multipart rotor according to the prior art in which a spur toothing 3 a is arranged on a diameter that is smaller than the outer diameter of the rotor. A free space 10 a is provided to accommodate the tool movement for producing the spur teeth and must be closed by a filling piece 11.

It is the object of the invention to provide an improved rotor for a flow machine.

In order to meet the above-stated object, a rotor according to the preamble of claim 1 is further developed by its characterizing features. Claim 13 claims protection for a flow machine with a rotor according to the invention, and the subclaims claim protection for preferred developments.

Apart from rotor blades which are constructed integral with the disks, it is also known to detachably fasten rotor blades to the disks in that a blade root of the corresponding rotor blade is secured in radial direction by positive engagement in a correspondingly shaped groove in axial or circumferential direction of the rotor which preferably has one or more undercuts for this purpose. In this connection, FIG. 2 shows a rotor blade 8 whose blade root is inserted into an axial groove and a rotor blade 9 whose blade root is held in a circumferential groove. The blade root can be secured in the groove in an insertion direction by intermediate pieces or closing pieces or by adjoining blade roots which are wedged in or screwed in, for example.

The invention proposes that the separating planes of at least two disks are positioned in a groove of the kind mentioned above which is provided for receiving a blade root of a rotor blade. In this way, a free space required to allow for the withdrawal of the tool is closed by the rotor blade root of the corresponding stage at the same time.

To this end, a multipart bladed rotor, according to the invention, for a flow machine, particularly a gas turbine or steam turbine or an axial compressor, has two or more disks whose front sides, which face one another, are connected to one another in a separating plane so as to be fixed with respect to rotation relative to one another, wherein a groove receiving one or more rotor blade roots is formed in this separating plane.

In this way, production costs and assembly costs for the filling pieces can advantageously be eliminated. At the same time, this can advantageously prevent a weakening of the structure of the rotor, particularly an interruption in the flow of force in the rotor, but also interference in the flow owing to an additional free space in addition to the groove which is required in any case for receiving the blade root. Another advantage can consist in that the manufacture, particularly the cutting manufacture, and monitoring of the groove which is formed so as to be axially divisible by means of, and to the extent of, the separating plane is facilitated.

The two disks can be detachably connected to one another, particularly by positive engagement, so as to be fixed with respect to rotation relative to one another. To this end, in a preferred embodiment of the present invention, a spur toothing, particularly a Hirth-type toothing or a Gleason-type toothing, is formed in the separating plane. The at least two disks can then be connected to one another axially by one or more tie rods. In an alternate construction, the two disks can also be non-detachably connected, e.g., welded, to one another in the separating plane. The two forms can also be combined in that one disk is detachably connected to an adjacent disk, particularly by a spur toothing, and non-detachably connected, particularly welded, to an opposite adjacent disk.

In the present case, the disks are particularly rotationally symmetrical portions of the rotor.

Grooves for blade roots can extend in axial direction of the rotor as is known, e.g., from DE-OS-1 182 474. In this case, it is advantageous when every tooth base of a spur toothing terminates in an axial groove of this kind which accordingly allows for the required tool clearance. However, the groove is preferably a groove extending in circumferential direction of the rotor for receiving a plurality of blade roots which are distributed along the circumference. For this purpose, the groove can have a fir-tree cross section. Within the meaning of the present invention, a fir-tree cross section is characterized in that it has one or more undercuts in radial direction, behind which corresponding projections of the blade root can engage so as to secure the blade root in radial direction by positive engagement.

In a preferred construction, a spur toothing extends radially in a groove base of the groove. This means that the spur toothing is arranged on the radial inner side of the groove formed at the outer circumference on a diameter which is smaller than the outer diameter of the rotor.

The blade roots can advantageously be arranged between the two halves of the groove which are separated by the separating plane before connecting the two disks so that when the disks are joined they engage behind undercuts of the groove which is then closed. In this case, there is no need for an insertion flank in the circumferential groove such as is provided for inserting the blade roots in grooves which are formed in one-piece disks. Therefore, in a preferred construction, the groove can have a cross section which is substantially constant in circumferential direction of the rotor.

The separating plane can be formed axially at any point on the groove. It preferably extends substantially through the centroid of a groove cross section so that the blade root is supported approximately equally in both disks. In particular, the groove can be formed substantially symmetric to the separating plane. By symmetry is meant in the present context not only a mathematical symmetry in which the contour of one disk in an axial section corresponds to the complementary contour of the other disk, but also a functional symmetry, for example, the forming of undercuts which correspond to one another but which can be offset relative to the other disk particularly in radial direction. This is especially advantageous in gas turbine compressor rotors in which the outer radius of the rotor hub generally increases in the direction of flow in order to allow for the increasingly compressed fluid.

One or more additional rows of blades can be provided parallel to the separating plane on one or both disks so that a disk of this kind forms a plurality of stages of the flow machine. Additional rows of blades of the kind mentioned above can also be fastened in a positive engagement by means of blade roots held in additional grooves or can be formed integral with the disk, i.e., by primary shaping, or can be non-detachably connected, e.g., welded or riveted, to the disk. Also, a combination is possible in which one or both disks have blades which are held in grooves and also have blades which are formed integral with the disk.

In a flow machine according to the invention with a multipart bladed rotor, two or more disks can be connected to one another so as to be fixed with respect to rotation relative to one another in a separating plane in which a groove is formed for receiving one or more blade roots.

Further advantages and features of the present invention follow from the subclaims and embodiment examples. The partially schematic drawings show:

FIG. 1 an axial half-section through a gas turbine according to an embodiment of the present invention;

FIG. 2 an axial partial section through two rotor blades on disks of a prior-art rotor which are connected to one another in a separating plane; and

FIG. 3 a partial view corresponding to the view in FIG. 2 showing two disks of a rotor, according to an embodiment of the invention, which are connected to one another in a separating plane.

FIG. 1 shows an axial half-section through the upper half of a gas turbine according to an embodiment of the present invention. A compressor rotor 1 of the gas turbine is constructed as a disk-type rotor, wherein each disk 2, as a so-called multidisk, has a plurality of rows of rotor blades 5 which are distributed along the circumference, these rows being arranged axially one behind the other. The blade roots of the rotor blades 5 are held in corresponding grooves 6 in circumferential direction of the rotor 1. The grooves 6 have assembly openings which make it possible to insert the blades (not shown).

The disks 2 are positioned relative to one another by means of Hirth-type spur teeth 3 or Gleason-type teeth and are clamped by screws or tie rods 4 to form a rotor composite.

In a rotor according to the prior art, a section of which is shown in FIG. 2, the separating planes 7 a of the multidisks are arranged between grooves of two adjacent blade rows 8 and 9. Since the Hirth-type spur toothing 3 a is arranged on a diameter which is smaller than the outer diameter of the compressor disks, a corresponding free space 10 a must be provided to allow for the withdrawal of the tool for the process of producing the toothing 3 a. This free space 10 a must be closed with corresponding filling pieces 11 when assembling the rotor to ensure a continuous hub contour and, therefore, a continuity of the inner wall 12 of the flow channel 13 of the gas turbine.

In a rotor according to an embodiment of the present invention, shown in FIG. 3, such as can be used, for example, in a gas turbine according to FIG. 1, the separating plane 7 of adjacent multidisks is situated in the plane of symmetry of a groove 10 for receiving blade roots 14 of rotor blades 5. The Hirth-type spur toothing 3 is arranged radially below this groove 10 which is divided axially in this way. This arrangement has the advantage that the groove 10 can be used at the same time as free space to allow for the withdrawal of the tool for producing the Hirth-type spur toothing 3.

The groove 10 is closed by the roots 14 of the compressor rotor blades 5 of the corresponding stage when the rotor is assembled.

This arrangement has the advantage that the additional filling piece 11 can be dispensed with. Further, the manufacture and monitoring of the surfaces 15 in the axially divided groove 10 is facilitated.

In another construction, not shown, the blades of the stages between the separating planes are formed as an integral component part of the disks (bladed disk or BLISK).

List of Reference Numbers

-   1 compressor rotor -   2 disk -   3, 3 a Hirth-type spur toothing -   4 tie rod -   5 rotor blade -   6 groove -   7, 7 a separating plane -   8, 9 blade row -   10 groove -   10 a free space -   11 filling piece -   12 inner wall -   13 flow channel -   14 blade root -   15 surfaces 

1-13. (canceled)
 14. A multipart bladed rotor (1) for a flow machine, comprising: at least two disks (2) having front sides facing one another, said disks being connected to one another in a separating plane (7) so as to be fixed with respect to rotation relative to one another, said disks defining a groove (10) formed in the separating plane for receiving a blade root (14) of at least one rotor blade.
 15. The rotor according to claim 14, wherein said disks are connected to a spur toothing formed in the separating plane.
 16. The rotor according to claim 15, wherein said groove comprises a groove base and wherein said spur toothing extends radially in said groove base of said groove (10).
 17. The rotor according to claim 14, wherein said groove comprises a groove cross-section and a centroid, said separating plane extending substantially through said centroid of said groove cross section.
 18. The rotor according to claim 17, wherein said groove is formed substantially symmetric to said separating plane.
 19. The rotor according to claim 14, wherein said groove has a fir-tree shaped cross section.
 20. The rotor according to claim 14, wherein said groove is extending in circumferential direction of the rotor for receiving a plurality of blade roots which are distributed along the circumference.
 21. The rotor according to claim 20, wherein said groove has a cross section which is substantially constant in circumferential direction of said rotor.
 22. The rotor according to claim 14, comprising at least one additional row of blades on at least one of said two disks parallel to said separating plane.
 23. The rotor according to claim 22, additionally comprising a second groove and wherein a second row of blades is fastened in a positive engagement by means of blade roots held in said second groove.
 24. The rotor according to claim 22, wherein said additional row of blades is formed integral with said disk.
 25. The rotor according to claim 14, additionally comprising a tie rod and wherein said at least two disks are connected to one another axially by means of said tie rod.
 26. A flow machine having a multipart bladed rotor according to claim
 14. 27. The rotor according to claim 15, wherein said spur toothing is one of a Hirth-type toothing and a Gleason-type toothing
 28. The flow machine of claim 26, wherein the flow machine is selected from the group consisting of a gas turbine, a steam turbine and an axial compressor.
 29. The rotor according to claim 14, wherein said at least two disks are connected by positive engagement. 